For ANH, the PAL master looks to be consistently better (in terms of having less DVNR applied) than the NTSC. It also appears to be from a different telecine session - colour timing, framing and certain dirt spots are all different.

For ESB, generally the NTSC master is better, except for the instances where bright lights are moving at speed which results in the weird artefacts seen in the Vader's lightsabre and the Millennium Falcon's engine. The noise reduction hardware probably had different settings for concealing light scratches and dark dirt spots.

We don't know at the moment what ROTJ is like.

We are also assuming that there are only two (THX) masters: the PAL masters used for the French, German and Spanish LDs and the NTSC masters used for the DC and Faces releases in the US and Japan.